Apparatus for increasing the effective radiation of electromagnetic waves.



No. 767,974. PATENTED AUG. 16, 1904.

J. S. STONE. APPARATUS FOR INCREASING THE EFFECTIVE RADIATION OFELECTROMAGNETIC WAVES.

APPLICATION rILnn 001230, 1903. no IODEL.

WITNESSES: I \/E UNITED STATES Patented August 16, 1904.

PATENT OEEicE.

JOHN STONE STONE, OE CAMBRIDGE, MASSACHUSETTS, ASSTGNOR TO TVILLIAlT ITV. STVAN, TRUSTEE, OF BROOKLINE, MASSACHUSETTS.

APPARATUS FOR INCREASING THE EFFECTIVE RADIATION OF ELECTROMAGNETICWAVES.

SPEGIFIGATIONforming part of Letters Patent No. 767,974, dated August16, 1904,

Application filed October 30, 1903.

To all whom it may concern:

Be it known that I, JOHN STONE STONE, a citizen of the United States.residing at Cambridge, in the county of Middlesex and State ofMassachusetts, have invented certain new and useful Improvements inApparatus for Increasing the Effective Radiation of ElectromagneticWaves, of which the following is a specification.

My invention relates to the transmission of signals by electromagneticwaves of a kind that were discovered and investigated by Prof. AndreEugene Blondel, of Paris, in. 1898, and it more particularly relates toapparatus for increasing the effective radiation of these Waves from anelevated conductor.

The properties and characteristics of electromagnetic waves radiatedfrom an elevated conductor have long been well known and are clearly setforth in the following publications: Association Fremcais pomLAoemcement (lea Sciences, Comptc Renela ele la 27 Secs i071, Nantes,August 11, 1898, part 2, page 212, Prof. A. E. Blondel; Seances cle laSoc'z'ete Frmzcm's ele Physique, Paris, May 5, 1899, 2 fascicule, pageA8, Dr. Andre Broca; Electrical Rem'ew, Vol. 44, May 5, 1899, London,page 746, Blondel; Electrical Review, Vol. 44, May 12 and 19, 1899,London, pages 795 and 799, J. E. Taylor; CbmpteaRemlas (lea Seances (lcLAcaelemle eles Sciences, Tome OXXX, May 21, 1900, Paris, page 1383,Blondel. A brief exposition of the theory of the radiation ofelectromagnetic waves from an elevated conductor is also to be found inthe United States Patent No. 706,7 46, dated August 12, 1902, to whichreference is herein made for further information concerning their'properties and mode of propagation. Attention, however, is called to aninaccuracy in the paper, hereinbefore referred to, read by Blondelbefore the French Association for the Advancement of Science-via, thatcurrents are developed byelectromagnetic waves in a plate of conductingmaterial interposed between the sparkterminals of a Hertz oscillator inthe equatorial plane thereof, whereas this plate being in theequatorialc'. c., the'equipotentialplane Serial No. 179,223. (No model.)

of the oscillator will have no currents devel- 5 oped therein exceptsuch currents as are created therein in the immediate neighborhood ofthe oscillator, owing to the fact that the lines of electric force arenot everywhere normal to the equatorial plane until a point equal to aquarter-wave length of the transmitted wave away from the oscillator isreached. Likewise when the elevated conductor is grounded no currentsare created in the earth, which is then the equatorial or equipotentialplane of the vertical oscillator or elevated conductor, except suchslight currents as are created therein in the immediate neighborhood'ofthe transmitting-wire, owing to the fact that the lines of electricforce are not 5 everywhere normal-to said surface until the quarter-wavelength is reached and also owing to the fact that the surface of theearth is not a perfect conductor and except such currents as are createdtherein when this surface over 7 O which the waves travel suddenlychanges direction. Attention is further called to an inaccuracy inPatent No. 706,746, in which is repeated the same error which is to befound in the-paper, above mentioned, by J E. Taylor in the LondonElectrical Reciew-viz., that the energy received by a given aerialvaries inversely as a given distance, whereas said energy variesinversely as the square of a given distance.

Having thus set forth the bibliography of electromagnetic -wavepropagation from a grounded elevated conductor and having cautionedthose wishing to practice this invention against the errors found insuch bibliography, 8 5 it will be necessary only to explain in thisspecification that these Waves are radiated by creating electricoscillations in a grounded elevated conductor, preferably verticallyelevated; that they consist of two components, 9 one of whichtheelectricis normal to the surface of the earth, and the other of whichthe magnetic-is parallel to the surface of the earth, as set forth in myLetters Patent No. 725,634, April 14, 1903, and that they travel 95 overthe surface of the earth, water, or other natural media with which saidelevated conductor or transmitting-wire is connected, even and 714,832,dated December 2, 1902.

, although all parts of said surface of the earth,

water, or other natural media do not lie in the same plane or in thesame straight line. I have experimentally determined that the effectiveradiation of these waves can be increased by artificially increasing thenatural electrical conductivity of the surface of the earth or othernatural media in the immediate vicinity of the base of thetransmittingwire and maintaining said surface in a constantly-conductingstate. I have also determined that the area of this surface necessary tobe maintained in amore highly conducting condition in order that theradiation may be most effectively increased is the area of a circlewhose center is the base of the elevated conductor and whose radius isequal approximately to a quarter-wave length of the transmitted wave. Ithas sometimes been observed that on hot dry days it is impossible totransmit electromagnetic waves from a grounded elevated conductor. Ihave experimentally determined that this breaking down of awireless-telegraph transmitting system cannot occur if the naturalelectrical conductivity of the surface of the earth surrounding the baseof the elevated conductor be increased by artificial means andmaintained in such state of increased electrical conductivity in themanner described in this specification.

4 In the drawing which accompanies and forms a part of thisspecification the figure is a diagrammatic illustration of oneembodiment of my invention. 7

In the figure, a is a source of varying electromotive force, which ishere shown. as an alternating-current generator. k is a key. T is astep-up transformer. O is a condenser. s is a sparkgap. L is aninductance. M is a transformer, preferably a step-up transformer. V isan elevated conductor or transmitting-wire. Gr represents in diagrammeans whereby the natural radial electrical conductivity of the surfaceof the earth in the neighborhood of the base of the elevated conductoris increased and maintained in a highlyconducting state.

For the construction of the transmitting apparatus and circuitarrangements and the mode of operation thereof reference may be had tomy prior Letters Patent Nos. 714,756 It is sufiicient to here state thatby means of the apparatus made in accordance with the specifications ofsaid Letters Patent electrical oscillations which preferably approximatethe sinusoidal or simple harmonic form as closely as practicable areimpressed or forced uponthe elevated conductor either inductively orconductively connected with the sonorous or closedpersistently-oscillating circuit M L C 8. However, the transmittingapparatus and circuit arrangements herein shown are merely intended tobe illustrative of any transmitting system, and it is to be understoodthat unless otherwise stated I do not desire my claims to be limited toany particular transmitting system, inasmuch as it is obvious that myinvention may be used with any system whereby the radiation ofelectromagnetic waves is effected.

For making the surface of the earth more highly conducting andmaintaining it in a constantly-conducting state a multiplicity ofsubstances may be used. In the drawing I have illustrated one embodimentof my invention in which metallic wire-netting of large mesh, known aschicken-coop netting, is placedin electrical contact with the earthsurrounding the lower end of the elevated conductor and is connected tothe lower end of said conductor. Such netting has been used successfullyfor the purpose herein specified. I have also used a layer of commercialcalcium chlorid, although any other deliquescent salt which by virtue ofits moisture-absorbing properties will maintain the surface of the earthin a constantly-moistened condition may be used, and a layer of suchsalt may with advantage be spread upon the earth within the area coveredby the wire-netting. A solution of water and any conducting salt may beused. In fact, I have restored to eflicient working order a system bywhich radiation of electromagnetic waves was rendered impossible by heatand drought by merely moistening the earth with water for a distancefrom the base of the elevated conductor equal approximately to aquarter-wave length of the transmitted wave. Iron or other metallicwires disposed radially and circumferentially may be used and also rocksalt. coarse common salt, charcoal, coke, and, in fact, any substancewhich exhibits a greater degree of electrical conductivity than theearth. hen wire-netting or a system of radially and circumferentiallyextending metallic wires are so employed, it is to be noted that theefiect is virtually a substitution of said netting or metallic wires forthe earth as a natural guide for the electromagnetic waves.

I have discovered that in order to be most effective for the purposeabove specified the means whereby the natural electrical conductivity ofthe earth or other natural media is increased must extend from the baseof the elevated conductor a distance equal approximately to aquarter-wave length of the transmitted wave. The reason for this is thatthe true radiation of electromagnetic waves does not begin until a pointabout a quarter-wave length from the elevated conductor is reached,because it is well known that until this point is reached the electricand magnetic components of an electromagnetic wave are not in phase andthat slight electric currents are created in the earth up to this point.

Although it is indicated by theory that any means employed to increasethe natural electrical conductivity of the earth should extend of wiresor other means specified herein may be much smaller than the area of acircle whose radius is equal to a quarter-wave length of the transmittedwave, although better results are obtained as this area is approximated.

In my application Serial No. 179,222, filed simultaneously herewith, Ihave fully set forth the theory of radiation of electromagnetic wavesfrom an earthed elevated conductor.

Whereas heretofore it has been alleged that by means of a constructionsomewhat-similar to that described herein, but in the form of aconducting-strip extending from the transmitting-station in the generaldirection of the receiving-station, a certain directive effect may .beobtained, it is herein pointed out that no such directive eifect can beobtained in the manner alleged. In explanation of the foregoingreference is to be had to Huyghens princlple, which is applicable to allfree waves in an unlimited medium and by which the waves would proceedto spread in all directions as soon as they have passed beyond the limitof the conducting-strip laid upon the earths surface in much the sameway that sound-waves proceed to spread in all directions after leavingthe end of an organ-pipe, in which they are limited, and passing outinto the air. It is not with this alleged directive effect that thisinvention is concerned, and I desire it to be understood that I heredisclaim the use of the invention herein described for such purpose.

IVhereas heretofore it has been alleged that by means of a constructionsomewhat similar to that described herein the capacity and inductance ofthe vertical transmitting-wire are increased, or at least maintainedconstant, irrespective of climatic and other'conditions, such as changesof electrical conductivity of the surface of the earth in the immediateneighborhood of said transmitting-wire due to salt spray, &c., it isherein pointed out that even when the surface of the earth has theminimum natural conductivity possible under the most unfavorableconditions the capacity of the vertical wire is definite anduninfluenced by the degree of conductivity of the surface of the earthfor the same reason that the capacity of a condenser is uninfluenced bythe degree of conductivity of the metal employed for thecondenser-plates and that the inductance is completely determinedentirely irrespective of the conductivity of the surface of the earth,being dependent solely upon the geometric constants and material of saidwire. I therefore desire it to be understood that I here disclaim theuse of the invention herein described for such purposes.

A method of increasing the effective radiation of electromagnetic wavesfrom an earthed elevated conductor which may be carried out by theapparatus herein described has been claimed in my application Serial N0. 179,222, filed October 30, 1903.

I claim 1. In an apparatus for increasing the effective radiation ofelectromagnetic waves, an elevated conductor, for radiating saidelectromagnetic waves, conductively connected at its lower end to amaterial of greater electrical conductivity than that of the earth, saidmaterial being in electrical contact with the earth and extendingoutwardly in all directions from the lower end of said conductor for aradial distance equal approximately to a quarterwave length of thetransmitted wave, in combination with means for developingelectricaloscillations in said elevated conductor.

2. In an apparatus for increasing the effective radiation ofelectromagnetic waves, an elevated conductor, for radiating saidelectromagnetic waves, conductively connected at its lower end to amaterial of greater electrical conductivity than that of the earth, saidmaterial being in electrical contact with the earth and extendingoutwardly in all directions from the lower end of said conductor for aradial distance equal approximately to a quarterwave length of thetransmitted wave, in combination with means for developing simpleharmonic electrical oscillations in said elevated conductor.

3. In an apparatus for increasing the effective radiation ofelectromagnetic waves, an elevated conductor, for radiating saidelectromagnetic waves, conductively connected at its lower end to ametallic netting, said netting being in electrical contact with theearth and extending outwardly in all directions from the lower end ofsaid conductor for a radial distance equal approximately to aquarterwave length of the transmitted wave, in combination with meansfor developing electrical oscillations in said elevated conductor.

4:. In an apparatus for increasing the effective radiation ofelectromagnetic waves, an elevated conductor, for radiating saidelectro-' magnetic waves, conductively connected at its lower end to ametallic netting, said netting being in electrical contact with theearth and extending outwardly in all directions from the lower end ofsaid conductor for a radial distance equal approximately to aquarterwave length of the transmitted wave, in combination with meansfor developing simple harmonic electrical oscillations in said elevatedconductor.

5. In an apparatus for increasing the effective radiation ofelectromagnetic waves, an elevated conductor, for radiating saidelectromagnetic waves, conductively connected at its lower end to ametallic netting, said netting being in electrical contact with theearth, and a layer of a deliquescent salt disposed on the earth withinthe area covered by said netting.

6. In an apparatus for increasing the effective radiation ofelectromagnetic waves, an elevated conductor, for radiating saidelectromagnetic waves, conductively connected at its lower end to earth,means for creating electrical oscillations in said elevated conductorand means for artificially increasing the electrical conductivity of theearth in all directions from said elevated conductor for a radialdistance equal approximately to a quarter-wave length of the transmittedwave.

7. In an apparatus for increasing the effective radiation ofelectromagnetic waves, an elevated conductor, for radiating saidelectromagnetic waves, conductively connected at its lower end to earth,the electrical conductivity of which for a radial distance equalapproximately to a quarter-wave length of the transmitted wave isincreased by means of a layer of calcium chlorid.

8. In an apparatus for increasing the effective radiation ofelectromagnetic waves, an elevated conductor, for radiating saidelectromagnetic waves, conductively connected at its lower end to earth,the electrical conductivity of which for a. radial distance equalapproximately to a quarter-wave length of the transmitted wave isincreased by means of a layer of a deliquescent salt.

9. In an apparatus for increasing the effective radiation ofelectromagnetic waves, an elevated conductor, for radiating saidelectromagnetic waves, conductively connected at its lower end to earth,the electrical conductivity of which for a radial distance equalapproximately to a quarter-wave length of the transmitted wave isincreased by means of a material of greater electrical conductivity thanthat of the earth, substantially as described;

conductivity than that of the earth, said material being in electricalcontact with the earth or other natural medium and extending outwardlyfrom the lower end of said elevated conductor a distance sufiicientlygreat for the purpose specified, in combination with means fordeveloping electrical oscillations in said elevated conductor.

11. In an apparatus for increasing the effective radiation ofelectromagnetic waves, an elevated conductor, for radiating saidelectromagnetic waves, conductively connected at its lower end to amaterial of greater electrical conductivity than that of the earth, saidmaterial being in electrical contact with the earth or other naturalmedium and extending outwardly from the lower end of said elevatedconductor a distance sufiiciently great for the purpose specified, incombination with means for developing forced electrical oscillations insaid elevated conductor.

In testimony whereof I have hereunto subscribed my name this 30th day ofSeptember,

JOHN STONE STONE. Witnesses:

BENJ. F. HAINES, "ELLEN B. TOMLINSON.

